Problem with basics of including C++ code with coder (coder.ceval)

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Hi,
I'm trying to incorporate existing c++ functions into Matlab coder using coder.ceval, but am struggling to even get a basc example working. I've seen the C example here, but am struggling to get even a simple 'hello world working with c++.
I've written a functin 'helloWorld.cpp' as follows:
#include <iostream>
#include "helloWorld.h"
using namespace std;
double helloWorld(double inpt) {
cout << "Hello World!!!" << endl;
cout << "Input is " << inpt << endl;
return inpt;
}
And then made 'helloWorld.h' as follows:
#if defined __cplusplus
extern "C" {
#endif
#ifndef HELLOWORLD_H_
#define HELLOWORLD_H_
double helloWorld(double inpt);
#endif /* HELLOWORLD_H_ */
#if defined __cplusplus
}
#endif
My matlab function is then:
function out = helloWorld(inpt)
%#codegen
if coder.target('MATLAB')
fprintf('Hello World! \n');
fprintf('Input number is %d \n', inpt);
out = inpt;
else
out = 0;
source1 = 'helloWorld.cpp';
coder.updateBuildInfo('addSourceFiles',source1);
out = coder.ceval('helloWorld',inpt);
end
end
I tried to compile this using the coder app, calling it as:
inpt = 2.0; out = helloWorld(inpt);
But it fails, with the Target Build Log telling me:
helloWorld1.c: In function helloWorld:
helloWorld1.c:24:3: error: incompatible type for argument 1 of ‘helloWorld’
   return helloWorld(inpt);
   ^
helloWorld1.c:18:8: note: expected const struct emlrtStack *’ but argument is of type ‘real_T’
 real_T helloWorld(const emlrtStack *sp, real_T inpt)
        ^
helloWorld1.c:24:3: error: too few arguments to function ‘helloWorld’
   return helloWorld(inpt);
   ^
helloWorld1.c:18:8: note: declared here
 real_T helloWorld(const emlrtStack *sp, real_T inpt)
What am I doing wrong here?
Cheers,
Arwel

Accepted Answer

Darshan Ramakant Bhat
Darshan Ramakant Bhat on 18 Feb 2021
I changed the MATLAB file name to avoid the clash. Also added coder.cinclude as suggested by Walter.
function out = helloWorldWrapper(inpt)
%#codegen
if coder.target('MATLAB')
fprintf('Hello World! \n');
fprintf('Input number is %d \n', inpt);
out = inpt;
else
out = 0;
source1 = 'helloWorld.cpp';
coder.cinclude('helloWorld.h');
coder.updateBuildInfo('addSourceFiles',source1);
out = coder.ceval('helloWorld',inpt);
end
end
I was able create mex using the below command
>> codegen helloWorldWrapper -args {0} -report
Code generation successful: View report
>> helloWorldWrapper_mex(5)
Hello World!!!
Input is 5
ans =
5

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